Despite the effectiveness of laser photocoagulation, diabetes remains a leading cause of blindness in the United States. The means to further reduce visual loss from diabetes will likely come from reducing the progression of retinopathy. The Diabetes Control and Complications Trial (DCCT) showed that tight control can reduce the development and progression of diabetic retinopathy. However, to achieve the tight control, the DCCT enrolled predominantly well educated and highly motivated subjects, and used a complex health care team composed of nurses, dieticians, and counselors. Implementing such diabetes care, especially in inner city populations such as those served by King/Drew Medical Center, may not be possible. In addition, tight control increases the risk of severe hypoglycemic episodes which can be life-threatening and be harmful to patients with diabetes. Other than tight glycemic control, there is currently no effective medical treatment for diabetic retinopathy. One potential treatment is angiotensin converting enzyme (ACE) inhibitor therapy. ACE inhibitors have been shown to be effective in retarding the deterioration of renal function in patients with diabetic nephropathy. Limited data suggests that ACE inhibition may be effective in reducing diabetic retinopathy. ACE inhibitors may reduce the progression of retinopathy by reducing pressure induced damage on the retinal vasculature. In addition, ACE inhibitors may protect the retinal vessels from the effects of certain growth factors such as angiotensin. The current study aims to generate pilot data on the effectiveness of ACE inhibition on the course of diabetic retinopathy. This will be a placebo controlled, randomized, double-blind, study evaluating eighty patients with diabetic retinopathy without hypertension.The long-acting ACE inhibitor, enalapril, will be used to help maintain patient compliance. Patients will be followed for three years. Each patient will undergo continuous diabetic education during the trial. Glomerular filtration rate, proteinuria, serum renin/prorenin and HDL/LDL ratio have been reported to be indicators of end-organ risk and/or response to ACE treatment in diabetic patients with renal disease. These will be followed every four months in each patient. Retinopathy will be followed with serial fundoscopic evaluations (3x/yr) and yearly retinal photographs. The end point will be progression of diabetic retinopathy.